On 12/16/10 5:21 AM, Dmitry Lenev wrote:
> Hello Davi!
>
> * Davi Arnaut<davi.arnaut@stripped> [10/12/14 02:35]:
>> # At a local mysql-5.1-bugteam repository of davi
>>
>> 3520 Davi Arnaut 2010-12-13
>> Bug#42054: SELECT CURDATE() is returning bad value
>
> ...
>
>> Since this logic was being used due to ancient performance reasons,
>> the solution is to simply rely on time(), which nowadays is just a
>> wrapper around the somewhat fast gettimeofday function.
>
> Could you please elaborate when has this change occurred and what
> has changed?
I didn't look up the history. What I had found was this:
http://tinyurl.com/38bqrmq
Where time() is mapped to a gettimeofday.
But now I see that there is another time implementation:
http://tinyurl.com/282rn6n
that calls the time system call.
We need to find out what is the difference between libbc and libc.
> Looking at OpenSolaris sources (yes, I know it is discontinued) I still
> can see that time() uses systrap whereas gethrtime() uses something which
> is called *fast*" systrap.
gettimeofday also uses a "fast" systrap:
http://tinyurl.com/296f2vq
> Also I have found the following article claiming that using gethrtime
> gives boost to MySQL performance even on Solaris 10:
>
> http://developers.sun.com/solaris/articles/mysql_perf_tune.html
I find this article highly suspicious since this hack exist at least
since July of 2007. Also, obviously, the explanation there is simply
wrong as we _can't_ use gethrtime for timing.
> And finally please note that for 5.1 we still support Solaris 8 and 9:
>
> http://www.mysql.com/support/supportedplatforms/database.html
>
What is your point?
Regards,
Davi
